kris@tpki.toppoint.de (Kristian Koehntopp) (03/22/91)
lcs@remus.rutgers.edu (Lyle C. Seplowitz) writes: > What about 8-bitplanes of color? Looking at the time-slot allocation diagram in my old Hardware Reference Manual, I can see two unused video time slots per pixel in low-resolution mode. I don't know, if this has been asked before, but why are there no bitplanes 7 and 8 in low-resolution mode? Has it to do with 8 bit register bus adresses (only 256 16-bit custom chip registers?) or are there difficulties allocating space for the extra circuitry on the custom chips? I consider adding bitplanes 7 and 8 the cheapest way to expand the custom chips. By doing this, one would get 320*200 (320*256) and 320*400 (320*512) in 256 colors and (provided you expand the color registers to 6 or 8 bit per r, g and b) a 256K color HAM-mode. This are also spcifications of cheap 256KB VGA cards. Kristian Kristian Koehntopp, Harmsstrasse 98, 2300 Kiel, +49 431 676689 .sig (Heute ohne Sepp)
sschaem@starnet.uucp (Stephan Schaem) (03/25/91)
It will not be has easy now , since the 256 word table would not be consequtive with the 2.0 adition. But I dont know why it wasn't done the first time? I alway wonder why the cut down, since the gfx library only ask for it!
navas@cory.Berkeley.EDU (David C. Navas) (04/03/91)
In article <1991Mar24.203644.10678@starnet.uucp> sschaem@starnet.uucp (Stephan Schaem) writes: >It will not be has easy now , since the 256 word table would not be >consequtive with the 2.0 adition. >But I dont know why it wasn't done the first time? I alway wonder >why the cut down, since the gfx library only ask for it! The simple answer is (as the software guy says): It's a hardware problem. The chips are created using rather old technology, and as it is things are rather kludged to get the hires and productivity rates out of them. We need CMOS chips, that's all there is to it :) From a software point of view it'd probably be rather trivial. David Navas navas@cory.berkeley.edu 2.0 :: "You can't have your cake and eat it too." Also try c186br@holden, c260-ay@ara and c184-ap@torus
sschaem@starnet.uucp (Stephan Schaem) (04/03/91)
ok,ok. If you say its a hardware problem.what hardware problem?! $dff180 was the start of the color lookup table and no register other than color register where placed after $dff180 (not anymore!) And if you get hires 4bit you get lores 8bit... the only diferecne betwen hirs 4bit and lores 8bit is display delay time and use a 256 color table instead of 16. Like Half bright! was it hard to have 64 color register?! I'm sory but I dont see any hardware for both: true 6 bitplanes and making 8 bit available in lores... Or is it because it hase only 256 word addresing space?! and even in that case true 6 bit was posible. Anyone actually know why? Stephan.
peterk@cbmger.UUCP (Peter Kittel GERMANY) (04/04/91)
In article <1991Apr3.090055.8224@starnet.uucp> sschaem@starnet.uucp (Stephan Schaem) writes: > > ok,ok. If you say its a hardware problem.what hardware problem?! > $dff180 was the start of the color lookup table and no register other > than color register where placed after $dff180 (not anymore!) > And if you get hires 4bit you get lores 8bit... > the only diferecne betwen hirs 4bit and lores 8bit is display delay > time and use a 256 color table instead of 16. > Like Half bright! was it hard to have 64 color register?! Half bright still uses only 32 color registers, the others are computed in hardware in real time (a shift register?)! Now, 256 color registers would really make up for a big space on the chips, and this is simply not feasible with current NMOS technology. So we must wait until all this is transferred to CMOS where this indeed shouldn't be a big problem anymore. Disclaimer: I'm not in the hardware group, so I don't know whether there is already such a development planned or in the works, sorry. But as I said already: When you consider that the new custom chips in the A3000 are already CMOS, this means that CMOS is no foreign word for those guys. And I really hope to see someday our beloved chips in new technology, beating every competitor out of his boots :-))) -- Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk
farren@well.sf.ca.us (Mike Farren) (04/06/91)
sschaem@starnet.uucp (Stephan Schaem) writes: > Like Half bright! was it hard to have 64 color register?! Halfbrite doesn't use 64 color registers - just 32. -- Mike Farren farren@well.sf.ca.us